The present invention relates to a fertilizer composition, more specifically to a fertilizer composition to be applied or sprayed to the roots, stems, leaves or fruits of plants for the purpose of preventing the plants from developing physiological lesions due to the deficiency of nutrient elements such as calcium.
Plants require various nutrient elements for their growth, but such elements are not always present copiously in the soil. It is known that plants therefore suffer obstruction of growth when they are not supplied sufficiently with some of the elements. As respects the three major elements of fertilizer, for example, nitrogen (N) is a constituent (i.e. component) element of proteins, phosphorus (P) not only is a constituent (i.e. component) element of nucleic acids and phospholipids but also fulfills an important role in the energy metabolism and the synthesis and decomposition of substances, and potassium (K) discharges physiological functions of metabolism and mass transfer. Insufficient supply of these main components (i.e. elements) generally renders the growth of plants inferior. Further, calcium is an important component constituting plants themselves and cells thereof and plays the important role of balancing the metabolism system. It is, however, prone to cause symptoms of calcium deficiency and induce physiological lesions, for example, tip rot in tomatoes, core rot in white rapes and cabbages, bitter pit in apples, and tip burn in strawberries.
When the soil is deficient in nitrogen, phosphorus and potassium, it is a general practice to incorporate a chemical fertilizer thereinto. With the purpose of inhibiting the physiological lesions due to the deficiency of calcium, meanwhile, many attempts have been made to incorporate inorganic calcium or the like into the soil to thereby supply calcium to a plant through its roots. More often than not, however, the calcium thus supplied is not thoroughly absorbed into the plant because part of the calcium reacts with atmospheric carbon dioxide and escapes ultimately in the form of calcium carbonate into the underground, because the calcium reacts with other incorporated chemical fertilizer and consequently incurs inactivation, and because such a phenomenon leads to fertilizer application imbalanced between chemical fertilizer and calcium. Even when the calcium is absorbed somehow or other through the root of a plant, it often fails to reach the site at which the physiological lesion actually develops because this element incurs unusual difficulty in migrating inside the system of a plant. When it reaches the site at all, it takes a considerably long time to do so and it therefore fails to exert an immediate effect on the lesion.
In recent years, therefore, attempts have been made to protect plants, which will easily suffer from physiological lesions due to the deficiency of calcium, from such lesions by spraying a calcium fertilizer in the form of an aqueous solution directly on leaves and fruits of the plants.
Known calcium fertilizers to be applied by the above technique of foliage spray include such water-soluble calcium salts as calcium formate (JP-A 59-137384), calcium acetate (JP-A 60-260487), calcium propionate (JP-A 4-202080), calcium chloride and calcium nitrate and so on. Further, calcium fertilizers obtained by combining highly soluble calcium salts with lowly soluble ones have been also known (JP-A 7-10666). Meanwhile, WO98/06681 publicly opened on Feb. 19, 1998 discloses the addition of heptonic acid or sodium heptonate and a surfactant to fertilizers.
The foliage spray of the aqueous solution of a calcium salt, however, had the problem of poor absorption efficiency because the absorption of calcium through the leaves and the fruits of a plant was generally low. Further, an effort to spray an excess of a fertilizer such as N, P, K or calcium salts for the purpose of enhancing the absorption thereof ironically results in imparting stress to the plant and causing toxic damage to the plant.
The inventors of the present invention have made intensive studies for the purpose of solving the above problems and have found that when a fertilizer composition comprising a combination of a specific anionic surfactant or a hydrophilic nonionic surfactant with a fertilizer, particularly a calcium compound is applied to the roots or leaves of a plant in the form of an aqueous solution or an aqueous dispersion, the plant can efficiently absorb the fertilizer, particularly calcium. The present invention has been accomplished on the basis of this finding.
The present invention provides a fertilizer composition comprising 0.1 to 30% by weight of (A) at least one anionic surfactant selected from the group consisting of carboxylic acid type surfactants, sulfuric ester type surfactants, phosphoric ester type surfactants and naphthalenesulfonic acid type surfactants or at least one hydrophilic nonionic surfactant, 1 to 60% by weight of (B) a fertilizer, and 0.01 to 10% by weight of (C) an organic acid, exclusive of heptonic acid, or a salt thereof. Hereinafter, xe2x80x9can organic acid, exclusive of heptonic acid, or a salt thereofxe2x80x9d means not only exclusion of heptonic acid but also exclusion of a salt of heptonic acid.
That is, the present invention relates to a fertilizer composition characterized by containing an anionic surfactant selected from among carboxylic acid type surfactants, sulfuric ester type surfactants, phosphoric ester type surfactants and naphthalenesulfonic acid type surfactants or a hydrophilic nonionic surfactant and a fertilizer as the essential components. In particular, it provides a fertilizer composition which permits high-efficiency absorption of the fertilizer into a plant when sprayed on the leaves of the plant in the form of an aqueous solution or an aqueous suspension. Herein, the fertilizer is also a fertilizer-effective component.
Further, the present invention also provides a method for improving the absorption efficiency of the fertilizer (B) for a plant by applying the above fertilizer composition to the roots, stems, leaves or fruits of the plant.
Additionally, the present invention provides a method for supplying the fertilizer (B) to a plant by applying the above fertilizer composition to the roots, stems, leaves or fruits of the plant.
The anionic surfactant to be used in the present invention is one selected from among carboxylic acid type surfactants, sulfuric ester type surfactants, phosphoric ester type surfactants and naphthalenesulfonic acid type surfactants.
Examples of the carboxylic acid type surfactants include fatty acids each having 8 to 20 carbon atoms and salts thereof, polyhydric carboxylic acids and salts thereof, polyoxyalkylene alkyl ether carboxylic acids and salts thereof, polyoxyalkylene alkylamide. ether carboxylic acids and salts thereof, rhodinic acid and salts thereof, dimer acids and salts thereof, polymer acids and salts thereof, and tall oil fatty acids and salts thereof. Further, examples of the amino acid type surfactants include acylamino acid salts, salts of acylsarcosine, acyloylmethylaminopropionic acid salts, alkylamino-propionic acid salts, and acylamidoethylhydroxyethyl-methylcarboxylic acid salts; and examples of the imidazoline type surfactants include alkylcarboxymethylhydroxyethylimidazolinium betaines and alkylethoxycarboxymethylimidazolinium betaines.
Examples of the sulfuric ester type surfactants include alkyl sulfates and salts thereof, polyoxyalkylene alkyl sulfates and salts thereof, polyoxyalkylene alkylphenyl ether sulfates and salts thereof, tristyrenated phenol sulfates and salts thereof, and polyoxyalkylene distyrenated phenol sulfates and salts thereof.
Examples of the phosphoric ester type surfactants include alkyl phosphates and salts thereof, alkylphenyl phosphates and salts thereof, polyoxyalkylene alkyl phosphates and salts thereof, and polyoxyalkylene alkylphenyl phosphates and salts thereof.
Examples of the naphthalenesulfonic acid type surfactants include alkylnaphthalenesulfonic acids, xcex2-naphthalenesulfonic acid-formalin condensates, and alkylnaphthalenesulfonic acid-formalin condensates and salts thereof.
The alkyl or alkenyl chains of these compounds each generally have 8 to 20 carbon atoms, and the salts thereof include alkali metal salts (such as Na salts and K salts), ammonium salts, alkanolamine salts, aliphatic amine salts and so on. Further, the above anionic surfactants may be used each alone or as a mixture of two or more of them.
When any of the above surfactants contains a polyoxyalkylene group, this group is preferred to be a polyoxyethylene group and the number of molecules added is preferred to be in the range of 1 to 50.
The hydrophilic nonionic surfactant to be used in the present invention is one having an HLB value of 5 or above, preferably 8 or above, still preferably 10 or above, as calculated by the Griffin equation. Specific examples thereof include sorbitan fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene fatty acid esters, polyoxyalkylene glycerin fatty acid esters, polyglycerin fatty acid esters, polyoxyalkylene polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyalkylene sucrose fatty acid esters, resin acid esters, polyoxyalkylene resin acid esters, polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, alkyl(poly)glucosides and polyoxyalkylene alkyl(poly)glucosides. These nonionic surfactants may be used each alone or as a mixture of two or more of them. In general, the nonionic surfactants each contain as the hydrophobic group a hydrocarbon group having 12 to 18 carbon atoms. With respect to nonionic surfactants having polyoxyalkylene groups, the polyoxyalkylene groups are preferably polyoxyethylene groups wherein the number of molecules added is 1 to 50, still preferably 8 to 40.
Further, anionic and nonionic surfactants other than as the essential components in the present invention, and cationic and amphoteric surfactants may be used in the present invention in combination with the essential components.
The fertilizer composition of the present invention contains a fertilizer in addition to the above specific anionic surfactant or hydrophilic nonionic surfactant. Examples of the fertilizer include inorganic and organic substances containing N, P, K, Ca, Mg, S, B, Fe, Mn, Cu, Zn, Mo, Cl, Si, Na and other elements, among which calcium compounds are particularly preferable. Examples of the calcium compounds include inorganic calcium salts such as calcium chloride, calcium nitrate, calcium carbonate, calcium sulfate, quick lime and slaked lime; salts of calcium with organic acids such as acetic acid, formic acid and lactic acid; and salts of calcium with polyaminocarboxylic acid type chelating agents such as ethylenediaminetetraacetic acid, and fatty acids, which may be used also as a mixture of two or more of them. In particular, it is preferable to use a water-soluble calcium salt such as calcium chloride, calcium nitrate, calcium formate and calcium gluconate.
The fertilizer composition of the present invention generally comprises the anionic surfactant or the hydrophilic nonionic surfactant in an amount of 0.1 to 30% by weight and a fertilizer, particularly a calcium fertilizer in an amount of 1 to 60% by weight (in terms of calcium salt), and may further contain other optional components and water or a solvent for the balance, though the formulation thereof may be varied at need.
The fertilizer composition of the present invention can be further improved in absorption efficiency by adding thereto an organic acid having a chelating ability or a salt thereof. In particular, it is preferable that the organic acid be a hydroxycarboxylic acid such as citric acid, gluconic acid, malic acid and heptonic acid, an aminocarboxylic acid, still preferably one having a plurality of carboxyl groups and amino groups, e.g., polyaminocarboxylic acid such as ethylenediamine-tetraacetic acid, ascorbic acid, or a polybasic acid such as oxalic acid. Examples of the salt include potassium salts, sodium salts, alkanolamine salts and aliphatic amine salts. Such an organic acid (or salt) may be contained in the composition in an amount of 0.01 to 10% by weight, preferably 0.1 to 5% by weight.
Although the fertilizer composition of the present invention may take any form selected from among solutions, flowable powders, wettable powders (as hydrates), granules (as particles), dusts (fine powders) and so on, aqueous liquid forms are particularly preferable from the standpoint of easiness of preparation of a dilution. In general, the composition is diluted to a conventional fertilizer concentration, particularly a calcium concentration of 1 ppm to 1%, preferably 50 ppm to 0.5% and then applied to the leaves or roots of a plant in the form of an aqueous solution, an aqueous dispersion or an emulsion.
Various means can be used for the supply of the fertilizer composition of the present invention to a plant. Examples of the means include direct spray of a diluted aqueous solution of the composition on the leaves, stems or fruits of a plant, injection of the aqueous solution into the soil, and addition of a dilution of the composition to the culture solution or feed water used in water culture or rock wool in contact with the roots of a plant.
The fertilizer composition of the present invention can be used as sprayed on various field crops and (domestic) garden plants because it causes no toxic damage to plants and enables plants to absorb calcium and other fertilizers efficiently.
The present invention will now be described by referring to Examples, though the present invention is not limited by them. Products 1 to 3 of the invention contain anionic surfactants according to the present invention, while Products 4 to 9 of the invention contain nonionic surfactants according to the present invention.